Apparatus for bending elongated metal articles



Feb. 13, 1945. D. B. NIVISON 2,369,486

' APPARATUS FOR BENDINQ ELONGATED METAL ARTICLES Filed July 18, 1941 //I 1 IA Patented Feb. 13, 1945 UNITED STAT APPARATUS FORVBENDING ELONGATED t METAL ARTICLES.

David Bruce Nivison, Brough,,England, assignor to. Blackburn Aircraft Limited, Brough, England Application July 18, 1941, Serial No. 403,024

, In Great Britain July 19, 1940 4 Claims. (Cl. 153-32) Th present invention is mainly concerned with the production of bent tubes, but it is conceivable that the general nature of the bending operation may also be applicable'to the bending of lengths which'are not necessarily of complete tubular-form. 'Thus, it is contemplated that 1 lengths of semicircular or other curved profile, channel, angle, or other sections may be bent out of their original longitudinal plane without necessarily or materially disturbing the profile. Forconvenience in the ensuing description and in the claims it is proposed touse the term tubes in a sense to cover such members as have been indicated above.

The invention ;.is especially concerned with means for bending which lend themselves to mass-production whilst at the same time producing a. finished article which is in no way inferior, and at least as to surface finish is even superior, to a product achieved as a result of normal handor machine-bending processes. I

It is also worthy of mention that by employment of the process and means afforded by the present invention it is a simple matter'to produce at a single operation a complicated bent formation which could be produced only with the greatest difiiculty by hand or by the machines at present employed.

In certain of its applications the invention involves the operation of constraining the tubes to slide with respect to a shaping die which is formed of gradually increasing curvature defining ultimately the formation. required to be imparted to the tube. Thus, where it is required to produce a complicated formation involving differently curved portions, or a very sharply curved portion, the shaping die may start with astraight.

portion or with a portion of a curvature of com- 7 imparted to the tube, and means for sliding the tube incontact with the surface of the die to ensure eventually the desired curvature. .j e n ;e ;ihe. Or i s m y b s h.

where certain ultimatejformations are required, that only the curves 0r bendsare actually defined by the dies so that intervening portions which are required to remain straight need not be engaged in a bending "operation, which procedure may very considerably simplify die. production and reduce expense, especially where the members to be bent have bends only, for instance, at one or both ends and/or at one or more spaced intermediate points.

Where a tube is likely to be subjected in the bending operation to such pressure that it is likely to crinkle at a bend, or' even collapse, the tube may be filled with some suitable medium which will prevent collapse but will not materially interfere with the bending operation.

Where the tubes are internally loaded the filling medium may be liquid or solid, or even some granulated or powdered medium which is able to afford the required resistance to collapse. If a solid medium is employed, it is convenient to follow the usual procedure adopted by coppersmiths in pipe-bending operations, according to which a closely-wound coil spring is first threaded through the tube, or positioned in the section, and is removed after the bending operation is completed. In many cases, however, it is preferred to use a solid and readily-bendable substance which may beused over and over again, and preferably one which can be heated to assume a liquid state. If the last-mentioned course be adopted tubes cut to size ready for bending may be fed through a bath of the heated liquid on a conveyor belt so that they become filled with liquid which, on the tubes passing out of the tank, sets solid. After the bending operation has been completed, thetubes may bereturnedto the same tank, or may be otherwise heated until the filling medium returns to its liquid form, whereafter it can Joev emptied from or shaken out of the tube.

I It is conceivable in some cases that any'filling medium may advantageously be left in the tube to increase its ultimate strength. i I

The invention also includes varying the crosssection of a bent tube subsequent to and preferablyin the same apparatus whichperforms the bending operation. Thus, for instance where it would'not be practical to bend a tube which is required ultimately to have a somewhat oval or streamline cross-section, the, shaping operation may be performed between dies which are not loaded highly enough to distort the cross-section during the bending operation, but which on being tion to the rest of the tube any particular sec-q tion, it may be desirable to perform the bending operation in one or more stages, perhaps-giving the tube an initial curvature which -may' even be different from that ultimately required before subjection to the final bending operation,

It is important to bear in mindthattlie bend ing operation may be in three dimensions. there may be bends up or down out of a horizontal plane, or laterally on each side of a ver tical plane, while any particularcurve may mi'cl'ude a bend with a longitudinal direction com onent. v o In some cases the tubes maybe subjected to heat-treatment during a bending operation, for which purpose the'dies may be heated. I b

To facilitate sliding of the tubes with respect to the shaping die or dies, they are preferably greased before being subjected to bending, and it may be mentioned that in many cases lead or zinc-faced dies, or dies formedof or faced with alloysincluding those metals, possess inherent lubricating properties which materially assist in carrying the invention into; efiect.

In order that it may be clearly understood and h readily carried into effect, the invention is hereinafter described with reference to the accompanying diagrammatic drawing, of which:

Figures 1, 2 and 3 taken together represent an exploded perspective View of a pressure meme ber, guide box and shaping die for producing "a relatively complicated pipe bend, as seen for instance in Figure 3.

Figures 4 and 5 are sections taken-longitude nally of the assembled guide box and shaping die showing the relationship of the associated-mem finished form at 223 in Figure 3, the stationary die is composed virtually of two's'e'para-te parts, 'vi'z., the shaping die shown in Figure Band the guide box shown in Figure 2. In the particular embodiment now under review the part shown in Figure 1 can be more aptly regarded as a pressure member rather than a movable die member. I

The shaping die itself is composed or the various sections 45 mounted in spaced relationshi on the base board 46, which'als'o mounts the back 41 which supports the curved sections 45 at their rear edges. It will be noticed that the straight tube 22B shownin broken lines in Fig ure 3 is engaging the leading ends of the'ourved sections 45, the curvature ofwhich increases gradually until the sections 45 collectively define the curvature required when the tube 223 has been constrained to slide over the incr asingly-curved surfaces of the sections 45 until it box shown in Figure 2 is positioned over the shaping die shown in Figure 3, the assembled condition of those members being shown more clearly in Figure 6. The guide box has a top plate 48 and a skeleton front frame 49, which mount spaced sections '59 complementary and opposite mime spacedse'ctionsw. Th'e'arrange ment is such that the spaced sections define a path of movement for the tube 223 to move down under pressure applied to the tube by means of the pressure member shown in Figis bearing upon the base 46; "mesons in;

tire -15 The path of movement for the tube is indicatedby the reference numeral 5! in Figure 6 and is thepart actually occupied by the tube shown in the sections of Figures 4; and 5. At its lower end the path 51 finishes at the base board--45, and at its upper end terminates in an opening provided by virtue of the fact that the rear upper edges of the sections 50 are spaced from the back 41 of the shaping die.

n is par-'ticiilarly important to notice with respect to Figure 3 that towards the righthand end the tube 22B is given an upward sweep by engagement with the inclined face 5i of the fixed block 52. Again, the lofthand endsection 4'5 develops a reentr'ant fa'ce, seen at 45, with which the curved'edge, shown in dotted lines at 50 in Figure 2, cooperates in spaced relation hip for'm'aihtaining the tube contiguous with the surrace 45. fFurthermore, the left'hand end of the tube 223 is: given a sweep somewhat 'rearwar'dly' inrelatioii to the b'ack4l due to the fact that it is constrained to slide down in Contact with the cut-away surface 47'.

It is obvious that practically any formation may be given to the tube 223 by forming the sections 4 9 and 5D appropriately. Likewise, if instead of the upward sweep being required at an end *of the tube an upward bend were required at some intermediate point, a surface operating with similar effect to that represented at 5| would be'provided-at the intermediate point. Conversely, if instead of an upward bend the tube reduiredfat some intermediate point a downward bend, the base board 46 would be appropriately'recess'ed fo're'ritr'y of the registering sec. tion of the tube into the recess under the influence of the pressure member.

"Referring now to the pressure member, which is shown by itself in Figure 1, the sections 53 are adapted to ihterdigitate withthe curved sections 45 of the shaping die and the constraining die members sn er theguide box and 'to engage the tube'and pres's it' down the path5l define-d betweenthe shaping die sections 45 "and the constraining die members '50 of the guide box. Th curved pressure section 54 is shaped so as to maintain "engagement with the tube when it is running down over the reentr a'nt surface 45'. Conveniently, the curve-d section 54 extends between the adjacent straight sections 53 at the lefthand'end of the assembly, the sections 53 beih'g securely attached to the 'urider'siirface of the toppla'te 55. i I H The shaping die shown in Figure 3 and the guide box shown in Figure 2 are positioned in their operative relationship by the locating battens '56 and 51.

in operation, the shaping' die an guide box are assembled as shown in Figure 6. The tube 223 is then entered through the side of the assembly to assume the position in which it is shown in broken linesin Figure 3 and in Figure 6. The assembly ;of the shaping die and guide box "and the insertion of the tube can easily be aaeaeae eiie'cted while the shaping die is positloned'on th bed of a press; the pressure member shown in Figure 1-is then inserted through theopenings 58 which are cut in the top plate 48 ofthe constraining die to receive the sections 53 and 54 of the pressure member. The pressure member is lowered as a whole until the lower ends of its sections rest upon the tube which is itself resting on the top of the shaping die sections. The ram of thepress is thenoperated, and consequently th tube 223 is forced from its chainline position shown in Figure 3 to move down in contact with the increasingly-curved surfaces of the sections 45 until it acquires the desired formation, when the pressure member is fully engaged in the shaping die and guide box assembly; The pressure member can then be withdrawn and the guide box and shaping die are separated for removal of the finished tube 223.

In case it hould be thought that the procedure of preparing a shaping die, guide box and pres-,

sure member for each peculiar tube-bending operation is a tedious and cumbersome one, it is particularly important to bear in mind that the invention is in this case particularly concerned with the massproduction of bent tubes. Thus,

.it follows that once the dies have been produced each. individual bent tube section can be shaped to its required formation in literally a matter of seconds; whereas a coppersmith working on a' required when the tube .is removed from the die. Such. provision may be necessary in some to the dies or equiv- In applying the pressure alent shaping means, any pressing machine may be employed, and if it is required to bend a fairly long tube only at spaced points, it is contemplated that the tube may be located in guides which may have open or separable portions so that portable ram and shaping means may be used at the several points.

What I claimis: I

1. Apparatus for bending tubes to a required formation comprising a plurality of spaced means collectively defining a stationary guideway of gradually increasing curvature, eventually defining the formation required, said guideway being of a uniform width not substantially greater than the external diameter of the tube to be bent,

spaced means defining a guideway.

and a plurality of spaced means for displacing a tube laterally through said guideway to impart the eventually defined formation of the latter thereto, said spaced displacing means moving as a unit in interdigitating relationship through said 2. Apparatus for bending tubes to a desired formation comprising cooperating means defining a stationary guideway of gradually increasing curvature eventually defining a desired contour guideway and in alignment therewith to effect gradually increasing curvature eventually defincases when operating with tubes which are formed of particularly springy-material, the additionally severe curvature being in that case specially chosen to ensure the proper formation of the tube when the constraining influence of the dies is'relieved.

In a, case where a tube has an end bent back upon itself as a plain bend throughg1809, it is to be understoodthat, though it is possible to effect such a bending operation by the provisionof a suitable die at one and the same operation as that employed to bend the tube intermediate its ends, it may in many cases be simpler first to in accordance with the deformation ofthe tube in'a different plane.

3. Apparatus for bending tubes to a desired formation comprising a plurality of spaced means collectively defining a stationary guideway of ing a desired contour in one plane, said guideway being of substantially uniform width not substantially greater than the external diameter of 'desired'formation to the tube, said spaced displacing means moving as a unit in interdigitating relationship through said spaced means defining the guideway.

4. Apparatus for bending'tubes to a required formation which comprisesmeans defining a con- 7 tour of the desired tube formation, pressure 1 means for gradually deforming a tube and shaping it to said contour, means restrainingsaid pressure means to move in a plane normal to the plane in which the tube is bent, and means for moving said tube in a direction having components both normal to and parallel to the'direction of movement of the pressure means, to cause the tube to be deformedto the desired contour. DAVID BRUCE NIVISON. 

